An image sensor device, such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor (CIS), has been widely applied on an electronic product such as a smart phone, a notebook or a tablet, etc. Due to miniaturization trend, the size of the image sensor device is restricted, while the size of each pixel are still required to be sufficiently large for maintaining sensing quality, and thus pixel resolution is limited. Therefore, it is one of the major tasks in this field regarding how to improve the pixel resolution without enlarging the size of the image sensor device and sacrificing sensing quality.
A conventional skill provides an image sensor device with stacked RGB sensing layers. Red, green and blue lights are absorbed at different depths of the RGB sensing layers in each pixel of such image sensor device, and hence higher pixel resolution is achieved. However, crosstalk issue may occur between adjacent stacked RGB sensing layers, resulting in signal-to-noise ratio (SNR) degradation.